How to make Selected item Should be highlited

[NallapatiMalleswari]

I am trying to change viewcontrollers using pickerview,But the selected item is not highlited while Changing viewcontrollers.This is my code ,Help me

func pickerView(_ pickerView: AKPickerView, didSelectItem item: Int) {
currentScrollIndex = item
print("currentScrollIndexSTEPS(currentScrollIndex)")
if item == 0{
let caloriesVC = self.storyboard?.instantiateViewController(withIdentifier: "CaloriesViewController")as! CaloriesViewController
caloriesVC.modalTransitionStyle = .crossDissolve
present(caloriesVC, animated: true, completion: nil)
}
else if item == 1{
let goalsVC = self.storyboard?.instantiateViewController(withIdentifier: "GoalsViewController")as! GoalsViewController
goalsVC.modalTransitionStyle = .crossDissolve
present(goalsVC, animated: true, completion: nil)
}
else if item == 2{
let oxigenVC = self.storyboard?.instantiateViewController(withIdentifier: "O2ViewController")as! O2ViewController
oxigenVC.modalTransitionStyle = .crossDissolve
present(oxigenVC, animated: true, completion: nil)
}

    preBtn.isHidden = (item == 0) ? true : false
    nextBtn.isHidden = (item == pickerViewItems.count - 1) ? true : false
}